Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 18 Jun 2013, 00:37

# If 5x=y+7, is (x−y)>0 ?

Author Message
TAGS:
Intern
Joined: 16 Feb 2012
Posts: 30
GPA: 3.57
Followers: 0

Kudos [?]: 6 [0], given: 0

If 5x=y+7, is (x−y)>0 ? [#permalink]  05 Jun 2012, 20:27
00:00

Question Stats:

36% (02:11) correct 63% (00:53) wrong based on 38 sessions
If 5x=y+7, is (x−y)>0 ?

(1) xy=6
(2) x and y are consecutive integers with the same sign
[Reveal] Spoiler: OA
Intern
Joined: 16 Feb 2012
Posts: 30
GPA: 3.57
Followers: 0

Kudos [?]: 6 [0], given: 0

Re: DS [#permalink]  05 Jun 2012, 20:43
Statement 1: xy=6 is not sufficient to answer the question because solving the equation gives y=3 when x is 2 and y is -10 when x is −3 5 .

5x=y+7

x=y+7 5 ................i

xy=6 ........................ ii

Replacing the value of x on eq ii: y(y+7) 5 =6

y 2 +7y=30

y 2 +10y−3y−30=0

y(y+10)−3(y+10)=0

(y+10)(y−3)=0

y=−10 or 3

If y=−10 , x=−3 5 . In this case, x−y=−3 5 −(−10)=47 5 . Yes.

If y=3 , x=2 . In this case, x−y=2−3=−1 . No.

In each case (x−y)>0 and <0 . Hence statement 1 is not sufficient.

Statement 2: If x and y are consecutive integers, x=2 and y=3 .

When x and y are consecutive integers, either x=y+1 or y=x+1 is possible.

(i) If x=y+1

5x=y+7

5(y+1)=y+7

4y=2

y=1 2 . Then x=3 2 . However this is not possible becase x and y are even not integers. So this option is not valid.

(ii) If y=x+1

5x=y+7

5x=x+1+7

4x=8

x=2

Then, y=3 . This is valid because x and y are consecutive integers.

So (x−y)=2−3=−1 . Hence statement 2 is sufficient.
Director
Status:
Joined: 24 Jul 2011
Posts: 504
GMAT 1: 780 Q51 V48
GRE 1: 1540 Q800 V740
Followers: 40

Kudos [?]: 165 [0], given: 9

Re: DS [#permalink]  06 Jun 2012, 07:23
If 5x=y+7 , is (x−y)>0 ?

Statement 1: xy=6
=> 5x = (6/x) + 7
=> 5x^2 - 7x - 6 =0
=> (x-2)(5x+3)=0
=> x = 2 or x= -3/5. So the solutions sets are (x,y) = (2,3) and (-3/5,-10). In case 1, x-y<0 and in case 2, x-y>0. Insufficient.

Statement 2: x and y are consecutive integers with the same sign.
Take x=k and y=k+1
=> 5k = (k+1) + 7 => k=2. So one possible solution is x=2,y=3.
Take y=k and x=k+1
=> 5(k+1) = k + 7 => k = 1/2. So no solution possible in integers.
Therefore x-y<0. Sufficient.

_________________

Free profile evaluation by top b-school alumni: email us at info@gyanone.com
B-school application service http://www.gyanone.com/appone.html

Last edited by GyanOne on 06 Jun 2012, 17:44, edited 1 time in total.
Senior Manager
Status: mba here i come!
Joined: 07 Aug 2011
Posts: 271
Location: Pakistan
Concentration: Strategy, Marketing
GMAT 1: 680 Q46 V37
GMAT 2: Q V
Followers: 14

Kudos [?]: 467 [1] , given: 48

Re: DS [#permalink]  06 Jun 2012, 10:52
1
KUDOS
GyanOne wrote:
=> x = 2 or x= -3/5. So the solutions sets are (x,y) = (2,3) and (-3/5,-10). In both cases, x-y>0. Sufficient.

isn't st-1 insufficient because of the above solution set?
if (x,y) = (2,3), then x-y=2-3 = -1. a 'no'
if (x,y) = (-3/5,-10), then x-y=-3/5+10= 47/5. a 'yes'

so, insufficient.
_________________

press +1 Kudos to appreciate posts

Director
Status: Gonna rock this time!!!
Joined: 22 Jul 2012
Posts: 552
Location: India
GMAT 1: 640 Q43 V34
GMAT 2: 630 Q47 V29
WE: Information Technology (Computer Software)
Followers: 1

Kudos [?]: 13 [0], given: 561

Re: If 5x=y+7, is (x−y)>0 ? [#permalink]  19 Feb 2013, 08:00
Bunuel,

x and y are consecutive integers with the same sign

Doesn't the above indicate that y is bigger than x by 1?
_________________

hope is a good thing, maybe the best of things. And no good thing ever dies.

Who says you need a 700 ?Check this out : http://gmatclub.com/forum/who-says-you-need-a-149706.html#p1201595

My GMAT Journey : end-of-my-gmat-journey-149328.html#p1197992

GMAT Club team member
Joined: 02 Sep 2009
Posts: 12081
Followers: 1876

Kudos [?]: 10079 [0], given: 955

Re: If 5x=y+7, is (x−y)>0 ? [#permalink]  19 Feb 2013, 08:28
Sachin9 wrote:
Bunuel,

x and y are consecutive integers with the same sign

Doesn't the above indicate that y is bigger than x by 1?

No, it dose not. When we are told that x and y are consecutive integers, it doesn't necessarily mean that y=x+1 (y>x), it could be that x=y+1 (x>y).

For example, check the following question: if-m-and-n-are-consecutive-positive-integers-is-m-greater-126287.html#p1031359

Hope it helps.
_________________
Director
Status: Gonna rock this time!!!
Joined: 22 Jul 2012
Posts: 552
Location: India
GMAT 1: 640 Q43 V34
GMAT 2: 630 Q47 V29
WE: Information Technology (Computer Software)
Followers: 1

Kudos [?]: 13 [0], given: 561

Re: If 5x=y+7, is (x−y)>0 ? [#permalink]  19 Feb 2013, 08:55
Bunuel wrote:
Sachin9 wrote:
Bunuel,

x and y are consecutive integers with the same sign

Doesn't the above indicate that y is bigger than x by 1?

No, it dose not. When we are told that x and y are consecutive integers, it doesn't necessarily mean that y=x+1 (y>x), it could be that x=y+1 (x>y).

For example, check the following question: if-m-and-n-are-consecutive-positive-integers-is-m-greater-126287.html#p1031359

Hope it helps.

Bunuel,
I checked The link you gave . There m has to be greater than n.
But here in this question, it is given that x and y are consecutive. Meaning of consecutive from google indicates that y follows x..

con·sec·u·tive
/kənˈsekyətiv/
Following continuously.
In unbroken or logical sequence.
Synonyms
successive - sequential - running - sequent - serial

So y has to be bigger than x right?
_________________

hope is a good thing, maybe the best of things. And no good thing ever dies.

Who says you need a 700 ?Check this out : http://gmatclub.com/forum/who-says-you-need-a-149706.html#p1201595

My GMAT Journey : end-of-my-gmat-journey-149328.html#p1197992

GMAT Club team member
Joined: 02 Sep 2009
Posts: 12081
Followers: 1876

Kudos [?]: 10079 [0], given: 955

Re: If 5x=y+7, is (x−y)>0 ? [#permalink]  19 Feb 2013, 08:59
Sachin9 wrote:
Bunuel wrote:
Sachin9 wrote:
Bunuel,

x and y are consecutive integers with the same sign

Doesn't the above indicate that y is bigger than x by 1?

No, it dose not. When we are told that x and y are consecutive integers, it doesn't necessarily mean that y=x+1 (y>x), it could be that x=y+1 (x>y).

For example, check the following question: if-m-and-n-are-consecutive-positive-integers-is-m-greater-126287.html#p1031359

Hope it helps.

Bunuel,
I checked The link you gave . There m has to be greater than n.
But here in this question, it is given that x and y are consecutive. Meaning of consecutive from google indicates that y follows x..

con·sec·u·tive
/kənˈsekyətiv/
Following continuously.
In unbroken or logical sequence.
Synonyms
successive - sequential - running - sequent - serial

So y has to be bigger than x right?

Google is not conducting the test, GMAC does.
_________________
Director
Status: Gonna rock this time!!!
Joined: 22 Jul 2012
Posts: 552
Location: India
GMAT 1: 640 Q43 V34
GMAT 2: 630 Q47 V29
WE: Information Technology (Computer Software)
Followers: 1

Kudos [?]: 13 [0], given: 561

Re: If 5x=y+7, is (x−y)>0 ? [#permalink]  19 Feb 2013, 09:44
lol
_________________

hope is a good thing, maybe the best of things. And no good thing ever dies.

Who says you need a 700 ?Check this out : http://gmatclub.com/forum/who-says-you-need-a-149706.html#p1201595

My GMAT Journey : end-of-my-gmat-journey-149328.html#p1197992

Re: If 5x=y+7, is (x−y)>0 ?   [#permalink] 19 Feb 2013, 09:44
Similar topics Replies Last post
Similar
Topics:
is x+y > 0? 6 22 Jan 2006, 23:14
DS- Is XY > 0 3 21 Nov 2007, 16:25
Is xy>0 6 02 Dec 2008, 09:17
Is xy > 0 ? 4 02 Jan 2009, 20:11
1 Is xy > 0? 7 16 Nov 2009, 14:27
Display posts from previous: Sort by